Login

u/Select_Cat_1549

r/Wastewater
▲ 5 r/Wastewater

Anyone else pull a pump for a tripping overload, and it turned out to be the contactor?

Had this in my head after the thread last week. Overload keeps tripping on a lift station pump, so the pump gets pulled. Then rebuilt. Then replaced. A week later it trips again, and the problem was a pitted contactor in the panel the whole time.

One pole ends up dropping a few volts when it should be close to zero. That phase runs low, and a small voltage unbalance turns into a much bigger current unbalance. The motor gets hot, overload trips, and the pump takes the blame.

Do you guys check voltage drop across the poles before you pull a pump, or is it mostly swap it and see?

reddit.com
u/Select_Cat_1549 — 10 days ago
▲ 37 r/Wastewater

After enough lift station call-outs, I started keeping track of what actually failed. It's almost never the pump.

I do control work on lift stations and SCADA, and the pattern on high-level calls is pretty consistent. The pump gets blamed first, and the actual fault turns out to be one of these:

  1. Level sensing - The transducer is greased over, or the float is tangled, so the panel thinks the well is lower than it is. The first thing I check is what the panel *thinks* the level is.

  2. Motor protection - A latched overload, seal failure, or the HOA left it off after maintenance.

  3. Control power - A blown control fuse, a dead 24 VDC supply, or a phase monitor that tripped during a storm and was set to manual reset.

  4. Comms - The station went quiet, and on a lot of SCADA systems, quiet looks the same as healthy.

I put together a short video walking through the quick field check for each one: [https://youtu.be/pnm6pjbjnuM?si=\_YNWthaaUstyGfX0\]

Full disclosure: it's my channel, and the narration is an AI clone of my own voice so I can get these out without a studio. Curious what's topped your list. Anybody else lose a night to a phase monitor?

u/Select_Cat_1549 — 16 days ago